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The HIDUINO project provides firmwares, documentation, and example code for building a class-compliant USB-MIDI device from an Arduino UNO or Mega 2560. HIDUINO does not use middleware software to convert serial messages through a MIDI loopback port (like LoopBe1 on Windows or IAC on OSX). Instead, HIDUINO provides a true USB-MIDI device for plug-and-play compatibility on Windows, OSX, and Linux - just like a commercial MIDI controller.

HIDUINO takes advantage of Arduino boards where a second AVR chip is used as the USB controller, so it won't work with single chip variants (e.g. Leonardo), nor older boards that use an FTDI chip as USB controller (e.g. Duemilanove). Many cheap Arduino knockoffs that pretend to be an Uno or Mega also might not work, since they tend to use the (slighly) cheaper FTDI chips.

HIDUINO is based on the LUFA framework by Dean Camera. HIDUINO was previously developed for robotic instruments and new musical interfaces @ the California Institute of the Arts.

The project name refers to a time when it was intended to contain many different USB-HID device types (joystick, mouse, keyboard, etc). The name "mididuino" is in use by an existing project, though it would be a more fitting title for this project.

Some good examples of HIDUINO in action:

mHzKontrol NotomotoN Diaktoros


The full list of requirements is listed on the wiki. At a bare minimum, you'll need:

MIDI Library

Since HIDUINO doesn't come with code for consuming or producing MIDI data in sketches themselves, a separate Arduino library must be used to encode/decode the MIDI format inbetween the HIDUINO firmware and the sketch. Notably, the standard Arduino midi library has not been updated to use the most recent "properties" file format, but details on this can be found on the wiki.


The Github wiki contains a host of information on working with HIDUINO. HIDUINO can be flashed onto the ATmega (8u2/16u2) chip on the UNO and Mega2560. Sketches cannot be bootloaded onto an Arduino while a HIDUINO firmware is loaded on the 8u2, so users can expect to switch between the default usbserial and HIDUINO firmwares regularly during development. The flashing process can be accomplished using an ISP (recommended) or through the DFU bootloader.

If using the ISP method, an easier way of development is to flash the USB controller chip with HIDUINO just once. Then, in the Arduino IDE, select "Upload Using Programmer" and connect the ISP to the header block near the main chip. This means the Arduino sketch can be flashed from the IDE without commandline interaction via an ISP or DFU. While HIDUINO is loaded onto the USB controller, do not attempt Serial communication via Serial.print()/println(): this will interrupt MIDI serial stream on the USB controller.

Flashing the arduino_midi firmware located in the compiled_firmwares directory: Note Remove the slashes in a program like Notepad if you are on Windows.

avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:arduino_midi.hex \
-U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m

The latest revisions (3+) of the Mega and UNO (and Due) use the Atmega 16u2 chip, so note the name changes of the default usbserial firmware below. On older revisions, the 8u2 chip is used. 8u2 firmwares are also included in the Compiled Firmware directory. The only important distinction between them is the product string that appears when an Arduino connects to a computer. avrdude will give a generic error if you try to flash an 8u2 chip with a 16u2 firmware and vice-versa. The at90usb82 chip profile is used for the following commands as it resembles both 16u2 and 8u2 -- one less thing to remember to change.

Flashing usbserial onto an UNO using an avrispmkii:

avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:usbserial_uno_16u2.hex \
-U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m

Flashing usbserial onto a Mega2560 using an avrispmkii:

avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:usbserial_mega_16u2.hex \
-U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m

Flashing usbserial onto a Due using an avrispmkii:

avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:usbserial_due_16u2.hex \
-U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m

A Note About Compiling

Compiling the firmware from scratch lets you change the name of the USB device (default HIDUINO).

Similar Projects

  • HID - MIDI-capable HID implementation for 32u4-based-Arduino boards (Leonardo) or Uno/Mega with custom bootloader
  • arcore - Similar to HID but only for USB-MIDI on Leonardo
  • mocoLUFA - Combined midi/usb-serial firmware


HIDUINO is released under the MIT license. HIDUINO inherits from the MIT license set by LUFA. A commercial license of LUFA is available for close-sourced products that do not wish to maintain MIT's attribution clause.